Re: [PATCH v2 2/6] perf test: Handle metric reuse in pmu-events parsing test

[John Garry]

On 01/04/2021 14:49, Jiri Olsa wrote:
On Thu, Mar 25, 2021 at 06:33:14PM +0800, John Garry wrote:
SNIP

+struct metric {
+       struct list_head list;
+       struct metric_ref metric_ref;
+};
+
+static int resolve_metric_simple(struct expr_parse_ctx *pctx,
+                                struct list_head *compound_list,
+                                struct pmu_events_map *map,
+                                const char *metric_name)
+{
+       struct hashmap_entry *cur, *cur_tmp;
+       struct metric *metric, *tmp;
+       size_t bkt;
+       bool all;
+       int rc;
+
+       do {
+               all = true;
+               hashmap__for_each_entry_safe((&pctx->ids), cur, cur_tmp, bkt) {
+                       struct metric_ref *ref;
+                       struct pmu_event *pe;
+
+                       pe = metrcgroup_find_metric(cur->key, map);

*

+                       if (!pe)
+                               continue;
+
+                       if (!strcmp(metric_name, (char *)cur->key)) {
+                               pr_warning("Recursion detected for metric 
%s\n", metric_name);
+                               rc = -1;
+                               goto out_err;
+                       }
+
+                       all = false;
+
+                       /* The metric key itself needs to go out.. */
+                       expr__del_id(pctx, cur->key);
+
+                       metric = malloc(sizeof(*metric));
+                       if (!metric) {
+                               rc = -ENOMEM;
+                               goto out_err;
+                       }
+
+                       ref = &metric->metric_ref;
+                       ref->metric_name = pe->metric_name;
+                       ref->metric_expr = pe->metric_expr;
+                       list_add_tail(&metric->list, compound_list);
+
+                       rc = expr__find_other(pe->metric_expr, NULL, pctx, 0);


Hi Jirka,

so this might add new items to pctx->ids, I think you need
to restart the iteration as we do it in __resolve_metric
otherwise you could miss some new keys

I thought that I was doing this. Indeed, this code is very much like 
__resolve_metric() ;)

So expr__find_other() may add a new item to pctx->ids, and we always 
iterate again, and try to lookup any pmu_events, *, above. If none 
exist, then we have broken down pctx into primitive events aliases and 
unresolvable metrics, and stop iterating. And then unresolvable metrics 
would be found in check_parse_cpu().

As an example, we can deal with metric test1, below, which references 2x 
other metrics:

    {
        "MetricExpr": "IDQ_UOPS_NOT_DELIVERED.CORE / (4 * (( ( 
CPU_CLK_UNHALTED.THREAD / 2 ) * ( 1 + CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE 
/ CPU_CLK_UNHALTED.REF_XCLK ) )))",
      "MetricName": "Frontend_Bound",
    },
    {
        "MetricExpr": "( UOPS_ISSUED.ANY - UOPS_RETIRED.RETIRE_SLOTS + 
4 * INT_MISC.RECOVERY_CYCLES ) / (4 * cycles)",
        "MetricName": "Bad_Speculation",
    },
    {
        "MetricExpr": "Bad_Speculation + Frontend_Bound",
        "MetricName": "test1",
    },

Does that satisfy your concern, or have I missed something?

Thanks,
John


jirka

+                       if (rc)
+                               goto out_err;
+               }
+       } while (!all);
+
+       return 0;
+
+out_err:
+       list_for_each_entry_safe(metric, tmp, compound_list, list)
+               free(metric);
+
+       return rc;
+
+}

SNIP

.